Method and apparatus for converting DC voltages at the top of a telecommunications tower

ABSTRACT

In one embodiment, an integrated power cable is provided. The integrated power cable, comprises a power cable having a first end and a second end; wherein the first end is configured to be electrically coupled to a DC power supply; at least one DC-DC voltage converter having at least one input and at least one output; wherein the second end is fixedly electrically and mechanically connected to the input; a first connector fixedly connected mechanically and electrically to the output; and wherein the first connector is configured to be coupled to at least one remote radio head.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of U.S. Patent Application Ser.No. 62/509,255, filed May 22, 2017; the entire content of theaforementioned patent application is incorporated herein by reference asif set forth herein in its entirety.

BACKGROUND

Modern cellular base stations are separated into two units, a basebandunit and a remote radio head. The baseband unit, or baseband system, islocated on the ground, often proximate to a tower. The baseband unitmodulates and demodulates digital data. Thus, for example, the basebandunit includes with a modulator and demodulator.

The remote radio head coupled to, and mounted proximate to, one or moreantennas on a tower. The remote radio head down converts and up convertsthe digital data to radio frequencies and amplifies received andtransmitted radio frequency signals. This respectively enhancesreception sensitivity and broadcast power of the cellular base stations.Thus, for example, the remote radio head includes an upconverter, a downconverter, a low noise amplifier, and a power amplifier.

However, the use of a remote radio head requires that power be suppliedto the remote radio head, on the tower, through a power cable. However,as disclosed in U.S. Pat. No. 9,448,576, because the length of the powercable can be hundreds of feet and the current drawn by the remote radiohead can be, e.g., about 20 Amperes at a voltage level of about fiftyvolts, the power loss due to the power cable can be significant. U.S.Pat. No. 9,448,576 is incorporated by reference herein as if set forthin its entirety.

Power loss attributable to the power cable is problematic, if thecellular base station needs to operate on backup battery power in theevent of a power blackout. The power dissipated by the power cable canbe sufficiently large to undesirably reduce the operating time of thecellular base station when powered by a battery backup system. Anequally undesirable alternative, due to increased cost, would be tocompensate for the loss by increasing the number of batteries in thebattery backup system.

To reduce the power loss, the voltage provided to the power cable can beincreased to proportionally reduce the current that must be provided topower the remote radio head. The reduction in current reduces powerdissipation by the square of the current reduction, or voltage increase.

U.S. Pat. No. 9,448,576 describes increasing the voltage applied to thecable above the maximum power rated input supply voltage for a remoteradio head, and then lowering that voltage, with a DC-to-DC convertermounted on the tower, to a level less than the maximum rated inputsupply voltage for the remote radio head.

In addition to enhancing the performance of the battery backup system,the reduced current reduces cellular base station power dissipation, orohmic losses, during normal operation, thus reducing operating expensesincurred by a cellular service provider. Alternatively, the cellularservice provider can decide to accept higher power loss by utilizingthinner wires in the power cable. In this case, the provider can reducecapital expenditures, e.g. copper conductor costs, while sacrificingoperating expenses.

However, operating at higher DC voltages can create risks for humans andcellular base station equipment. Also, DC-to-DC converters voltagelevels of relatively high power levels can generate high heat levels.Therefore, there is a need for a system that enhances safety. Further,there is a need for DC-to-DC voltage converter systems that can readilydissipate high heat levels. Further, there is a need for architecturesfor implementing cellular base station using higher voltages.

SUMMARY

In one embodiment, an integrated power cable is provided. The integratedpower cable, comprises a power cable having a first end and a secondend; wherein the first end is configured to be electrically coupled to aDC power supply; at least one DC-DC voltage converter having at leastone input and at least one output; wherein the second end is fixedlyelectrically and mechanically connected to the input; a first connectorfixedly connected mechanically and electrically to the output; andwherein the first connector is configured to be coupled to at least oneremote radio head.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a diagram of one embodiment of a cellular basestation;

FIG. 2 illustrates one embodiment of a high voltage DC-DC synchronousstep-down converter system;

FIG. 3 illustrates a diagram of one embodiment of an overvoltageprotection circuit;

FIG. 4A illustrates a diagram of one embodiment of a power cable with anintegrated at least one DC-DC voltage converter system;

FIG. 4B illustrates a diagram of another embodiment of a power cablewith an integrated at least one DC-DC voltage converter; and

FIG. 5 illustrates a block diagram of one embodiment of a co-packagedsystem comprised of a co-packaged first over voltage protection circuit,at least one DC-DC voltage converter system, and a second over voltageprotection circuit;

FIG. 6A illustrates a diagram of one embodiment of an enclosure, atleast one DC-DC voltage converter system, and a heatsink;

FIG. 6B illustrates a diagram of another embodiment of a DC-DC convertersystem;

FIG. 6C illustrates a diagram of an embodiment of the enclosure and theheatsink;

FIG. 6D illustrates a diagram of one embodiment of four DC-DC convertersystems, the first over voltage protection circuit and the second overvoltage protection circuit mounted in an enclosure;

FIG. 7 illustrates one embodiment of the first overvoltage protectioncircuit, at least one DC-DC voltage converter system and the secondovervoltage protection in separate enclosures;

FIG. 8A illustrates a block diagram of one embodiment of a combinationof at least one DC-DC voltage converter system and remote radio headcoupled through a converter connector and a remote radio head connector;

FIG. 8B illustrates a block diagram of one embodiment of at least oneDC-DC voltage converter system that provides power to multiple, separateremote radio heads;

FIG. 8C illustrates a block diagram of one embodiment of a remote radiohead incorporating at least one DC-DC voltage converter systemincorporated in a remote radio head;

FIG. 8D illustrates a block diagram of one embodiment of a powerdistribution unit system;

FIG. 9 illustrates a block diagram of one embodiment of a safety systemwhen converting high voltages at a top of a tower; and

FIG. 10 illustrates a flow diagram of one embodiment of operation of asafety system.

DETAILED DESCRIPTION

FIG. 1 illustrates a diagram of one embodiment of a cellular basestation 100. The cellular base station 100 includes at least one remoteradio head (RRH) 102 coupled to at least one antenna 104. The remoteradio head 102 and the at least one antenna 104 are mounted on a tower106. The remote radio head 102 is coupled to a baseband unit (BBU) 108.In another embodiment, the baseband unit 108 is not located on thetower, but in a building or enclosure, e.g. proximate to the base of thetower 106. In a further embodiment, the baseband unit 108 is coupled toa backhaul communications system 110. In yet another embodiment, thebackhaul communications system 110 couples the cellular base station 100to a core network of a cellular communications system.

In one embodiment, the remote radio head 102 is coupled, through atleast one DC-DC voltage converter system 121 and a power cable 122, to aDC power supply 112. In another embodiment, the at least one DC-DCvoltage converter system 121 is coupled to the DC power supply 112through a first overvoltage protection circuit (first OVP) 123. In afurther embodiment, the at least one DC-DC voltage converter system 121is coupled to the at least one remote radio head 102 through at leastone second overvoltage protection circuit (second OVP(s)) 125.

In one embodiment, the DC power supply 112 is coupled to the at leastone DC-DC voltage converter system 121 through a redundancy and safetysystem (RSS) 113. In another embodiment, a battery backup system (BBS)115 is coupled to the redundancy and safety system (RSS) 113. In afurther embodiment, a safety system may be substituted for theredundancy and safety system 113; the safety system may or may notinclude redundancy functionality to permit the use of the battery backupsystem in the event the DC power supply 112 fails.

In one embodiment, the DC power supply 112 generates a relatively highvoltage, e.g. 380-400 VDC. By raising the voltage level such arelatively high level, the current is proportionally reduced, and theohmic losses, e.g. in the power cable 122, is diminished by theproportional factor squared. As a result, conductor diameter of, and/orohmic losses in, the power cable 122 can be significantly reducedresulting in increased energy distribution efficiency and thus reducedcapital and operating costs. In another embodiment, because of thereduced current, conducting material other than copper can be used. Forexample, aluminium, although higher in resistance, is significantly moreabundant and cheaper than copper.

A first end 122A of the power cable 122 is coupled to the DC powersupply 112. A second end 122B of the power cable 122 is coupled to theat least one DC-DC voltage converter system 121, or the first OVP 123(if used). In one embodiment, the at least one DC-DC voltage convertersystem 121 is mounted on the tower 106. In other embodiments, to theextent each is used, the first OVP 123 and the second OVP(s) 125 aremounted on the tower 106. In a further embodiment, the DC-DC voltageconverter system 121, the first OVP 123 and the second OVP 125 aremounted proximate to the remote radio head 102.

FIG. 2 illustrates a block diagram of one embodiment of a highefficiency high voltage DC-DC synchronous step-down converter system221. The DC-DC synchronous step-down converter system 221 includes ahigh voltage DC-DC synchronous step-down converter 230 coupled to aconverter communications system 231. However, in another embodiment, thefirst communications system 231 can be located elsewhere, i.e. not inthe DC-DC synchronous step-downconverter system 221, on the tower 106,e.g. proximate to the remote radio head 102.

A synchronous step-down converter is utilized to provide the highefficiency for the high voltage DC-DC synchronous step-down converter230 and the cellular base station 100. In one embodiment, the highvoltage DC-DC step-down converter 230 is preferably one or more stagesof high efficiency DC-DC voltage converters. Each stage may be a buckconverter, a sine amplitude converter (or sine wave amplitudeconverter), a zero-current/zero resonance converter, an isolated flybackconverter, a LLC converter, or a LLC resonant half-bridge converter. Forexample, should highly regulated, high current output be required, thehigh voltage DC-DC synchronous step-down converter 230 can beimplemented as a single-phase or multi-phase buck converter. In anotherembodiment, the high voltage DC-DC synchronous step-down voltageconverter 230 can be implemented by two or more successive stages ofDC-DC buck voltage converters to diminish the input voltage 221A to alower desired, regulated output voltage 221B.

The high voltage DC-DC synchronous step-down converter 230 reduces aninput voltage (V_(DC IN)) 221A, e.g. 380-400V DC, to the desired,regulated output voltage (V_(DC OUT)) 221B, e.g. −48V, 12V, 5V, or 3.3V.If the high voltage DC-DC synchronous step-down converter 230 uses twoor more stages, the input voltage is successively reduced. For example,a first state may reduce an input voltage from 380/400V to −48V, and asecond stage reduces −48V to voltages more suitable for lower voltageelectronic devices such as 24V, 12V, 5V or 3.3V. Alternatively, morethan two stages can be used.

FIG. 2 illustrates the high voltage DC-DC synchronous step-downconverter 230 as a general purpose single stage, single-phasesynchronous converter. The illustrated high voltage DC-DC synchronousstep-down converter 230 includes a power controller circuit (controller)230C coupled to a driver circuit (driver) 230D. The driver circuit 230Dis coupled to switching elements 230E. In one embodiment, the switchingelements 230E are switching transistors such as power metal oxidesemiconductor field effect transistors. These switching elements 230Eare coupled to the input voltage 221A. In another embodiment, thecontroller 230C and driver 230D are combined, e.g. into a singleintegrated circuit, to drive switching elements 230E that remainseparate from such combination. The controller circuit 230C and drivercircuit 230D, whether separate or combined, require power from a lowvoltage converter (LV Conversion) 230M for powering internal logic. In afurther embodiment, the low voltage converter 230M is a DC-DC converterlike those described above, or uses a Zener diode. In yet anotherembodiment, the low voltage converter 230M is designed to operate with ahigh input voltage, e.g. 380-400V. In yet a further embodiment, lowvoltage converter 230M may be implemented like the high voltage DC-DCsynchronous voltage converter 230 but have more stages to provide alower output voltage. In one embodiment, the low voltage converter 230Mcan be part of the high voltage DC-DC synchronous step down converter,and e.g. comprise one or more additional stages of DC-DC voltageconversion; thus, there would not be a separate low voltage converter230M but just one or more additional stages of DC-DC voltage conversionin the high voltage DC-DC synchronous step down converter 230 to providethe lower DC voltage. In another embodiment, the controller circuit230C, driver circuit 230D, and the switching elements 230 may becombined, e.g. into a single integrated circuit.

The output of the switching elements 230E is coupled to a first terminalof a filter/snubber 230G. In one embodiment, the filter/snubber 230Gthat is implemented as a filter including a series inductor coupled to ashunt capacitor. The desired, regulated output voltage 221B is providedat a second terminal of the filter/snubber 230G. In yet anotherembodiment, the filter/snubber 230G is not used, and the switchingelements 230E are coupled directly to a transformer 230L which isolatesthe input voltage 221A (which can be a high voltage) from the load, e.g.the remote radio head(s) 102). In yet a further embodiment, thefilter/snubber 230G may be a snubber that removes high frequencyswitching spikes, e.g. a low resistance resistor and capacitor in serieswhich short to ground high frequency spikes from the output of SwitchingElements 230E. In another embodiment, the snubber could consist of afast acting Zener diode. The desired, regulated output voltage 221B isprovided at a second terminal of the filter 230G. In yet anotherembodiment, the filter/snubber 230G may include both a filter and asnubber.

In one embodiment, the DC-DC synchronous step-downconverter 230 includesa current sensor 230K and a first voltage sensor 230J which respectivelysupply a current feedback signal (I_(SENSE)) 230N and a voltage feedbacksignal (FB) 230P. The controller circuit 230C is configured to receivethe current feedback signal (I_(SENSE)) 230N and the voltage feedbacksignal (FB) 230P, and thus provide the desired, regulated output voltage221B. In another embodiment, the controller circuit 230C uses componentswithin the filter/snubber 230G for current sensing.

In one embodiment, the output of the filter/snubber 230G is coupled totransformer 230L. This embodiment provides isolation as described above.In another embodiment, a stage of rectification (rectifiers) 230R isused to oppose reverse current.

The converter communications system 231 is coupled to the power cable122. In one embodiment, the converter communications system 231comprises a first communications circuit 231B, a communicationsprocessing system 231C, a voltage sensor 231D, and a communicationssystem switch 231E. The first communications circuit 231B and thecommunications system switch 231E are coupled to the communicationsprocessing system 231C, and are configured to receive commands and/orcontrol signals from the communications processing system 231C. Thevoltage sensor 231D is coupled to the communications processing system231C and is configured to provide a signal representative of the voltagelevel at the input voltage 221A to the communications processing system231C.

In one embodiment, a first high voltage isolator (HV1) 231A, e.g. anoptical isolator, is used to isolate the first communications circuit231B from a high input voltage, while permitting the firstcommunications circuit 231B to transmit and receive data. In anotherembodiment, the high voltage isolator 231A may be a Bias Tee that splitsthe AC, e.g. RF, signals to the first communications circuit 231B (e.g.by means of an AC coupling capacitor) and the DC voltage to thecommunications system switch 231E (e.g. by means of a DC couplinginductor). In a further embodiment, the DC voltage from the Bias Tee maybe provided as the input voltage to the low voltage converter 230M andthe high voltage DC-DC synchronous step down converter 230. In thisembodiment, the low voltage converter 230M and the high voltage DC-DCsynchronous step down converter 230 are connected directly to the outputof HV1 231A and not to input voltage 221A as shown in FIG. 2. In anotherembodiment, the first communications circuit 231B is a power linecommunications circuit based on orthogonal frequency divisionmultiplexing such as Maxim Integrated Products, Inc. (Maxim's) MAX2990product or AISG (Antenna Interface Systems Group) compliant transceiverssuch as Maxim's MAX9947 product.

In one embodiment, the communications processing system 231C comprises amemory 231C-1 coupled to a processor 231C-2. In another embodiment, thememory 231C-1 includes a measurement and control system (MCS) 233, e.g.software executed on the processor 231C-2. The memory 231C-1 may be oneor more of semiconductor memory (such as Flash memory, read only memory,and/or random access memory), magnetic memory (such as a hard drive),and/or optical memory such as a DVD and optical reader. The processor231C-2 may be one or more of a microprocessor (such as an X86, PowerPC,or ARM based microprocessor), a digital signal processor, and/or amicrocontroller. In a further embodiment, all or part of thecommunications processing system 231C is implemented in whole or in partby an application specific integrated circuit and/or a fieldprogrammable gate array.

In one embodiment, the communications system switch 231E is a singlepole double throw switch implemented with field effect transistors. Inanother embodiment, the communications system switch 231E is configuredto receive both the input voltage 221A and the output voltage from thelow voltage converter 230M, and provide one of the voltages (andcorrespondingly supply power) to the communications processing system231C, the first communications circuit 231B, and/or the first highvoltage isolator 231A. Upon commencing operation, the communicationssystem switch 231E defaults to a providing the input voltage 221A, andcorresponding power, to itself and one or more of the communicationsprocessing system 231C, the first communications circuit 231B, and/orthe first high voltage isolator 231A. Based upon the voltage levelmeasured by the voltage sensor 231D, the communications processingsystem 231C determines whether the input voltage 221A, for exampleprovided from the redundancy and safety system 113, is a low voltage,e.g. 1.5-12V, or a high voltage, e.g. 380-400V. When the communicationsprocessing system 231C determines that the input voltage 221A is a highvoltage, then the communications system switch 231E switches so that itprovides the output voltage from the low voltage converter 230M, andcorresponding power, to itself and one or more of the communicationsprocessing system 231C, the first communications circuit 231B, and/orthe first high voltage isolator 231A. If the voltage sensor 231D and thecommunications processing system 231C detect that the voltage level ofinput voltage 221A reverts back to a low voltage, then thecommunications system switch 231E switches back to supplying the inputvoltage 221A at the output of the communications system switch 231E.

In one embodiment, upon becoming powered, and e.g. after initializing,the communications processing system 231C commands the firstcommunications circuit 231B to respond, e.g. with at least oneacknowledgement, to queries from the redundancy and safety system 113.In a further embodiment, the communications and switching control, andsensing functionality provided by the communications processing system231C is provided by the measurement and control system 233.

As described above, the cellular base station 100 may include a firstovervoltage protection circuit 123 and/or at least one secondovervoltage protection circuit 125. FIG. 3 illustrates a diagram of oneembodiment of an overvoltage protection circuit 300. The overvoltageprotection circuit 300 includes a fuse 300A, a first capacitor 300B, aZener diode 300C, a resistor (R) 300D, second capacitor 300E, athyristor 300F, and a Schottky diode 300G. The fuse 300A, which may be aresettable fuse, opens if the current drawn from a source by theovervoltage protection circuit 300 exceeds a limit. The first capacitor300B suppresses voltage spike and noise which may inadvertently triggerthe overvoltage protection circuit 300. The Zener diode 300C detects anovervoltage condition, raising the voltage on the gate of the thyristor300F. As a result, the fuse 300A is blown by the current flowing throughthe short circuit path created by the thyristor 300F.

The resistor 300D is a pull-down resistor which maintains a low voltageon the gate of the thyristor 300F when the Zener diode 300C is notturned on. The resistor 300D and capacitor 300E also serve as a snubbercircuit to prevent the thyristor 300F from being accidently turned on,e.g. when overvoltage protection circuit 300 is powered up. The secondcapacitor 300E prevents the overvoltage protection circuit 300 frominadvertently turning on.

The subsequently described techniques illustrate how a high voltage,e.g. 380-400V DC, can be supplied through the power cable 122 to powerat least one remote radio head 102 that is configured to receive a lowervoltage, e.g. −48V and has components that operate at lower voltages,e.g. 1.5-12V. FIG. 4A illustrates a diagram of one embodiment of a powercable with an integrated at least one DC-DC voltage converter(integrated power cable) 400. Thus, the at least one DC-DC voltageconverter systems 421 are made part of the integrated power cable 400,similar to how a connecter is integrated on one end of a cable. Thistechnique has the benefit that no additional equipment, e.g. at leastone DC-DC voltage converter system 121 need be mounted on the tower 106.Further, if the at least one DC-DC voltage converter system 121 isexposed to the environment, then no heatsink may be required todissipate heat from the DC-DC voltage converter system 121.

In one embodiment, one or more pairs of rail (e.g. high voltage) andground conductors 400C of the second end 422B of the power cable 422fixedly attached or connected, e.g. by mechanical and/or electricalmeans such as crimping and/or soldering, to at least one input 400D,e.g. corresponding input terminals, of the at least one DC-DC voltageconverter system 421. The at least one DC-DC voltage converter system421 also has at least one output 400E, e.g. output terminals, at whichregulated output voltage(s) are provided. In another embodiment, the atleast one output 400E forms a second end 400G of the integrated cable400. In a further embodiment, the first end 422A of the power cable 422forms the first end of the integrated power cable 400. In yet anotherembodiment, the first end 422A is configured to be coupled to the DCpower supply 112, e.g. through the redundancy and safety system 113. Inyet a further embodiment, the first end 422A is mechanically andelectrically fixedly connected to a second connector 400F which isconfigured to be connected, e.g. to the DC power supply 112 or theredundancy and safety system 113.

In one embodiment, the at least one output 400E is coupled, e.g. fixedlyconnected mechanically and electrically, to a first connector 400A. Inanother embodiment, the first connector 400A may part of the integratedpower cable 400; thus, the first connecter 400A is the second end of theintegrated cable 400. The first connector 400A can be used to couple theintegrated power cable 400, e.g. directly or through the at least onesecond overvoltage protection circuit 125, to the remote radio head 102.In a further embodiment, the first connector 400A is configured to becoupled to a connector of the remote radio head 102.

To protect the at least one DC-DC voltage converter system 421 and thesecond end 422B of the power cable 422 from the environment, in oneembodiment at least a portion of the at least one DC-DC voltageconverter system 421 and the second end 422B of the power cable 422 arecovered by an insulator 400B such as heat shrink tubing which is heatedto snuggly fit around all or part of such components, e.g. the secondend 422B of the power cable 422, the at least one DC-DC voltageconverter system 421, and the first connector 400A. In a furtherembodiment, a second connector is connected to the first end 422A of thepower cable 422.

FIG. 4B illustrates a diagram of another embodiment of a power cablewith an integrated at least one DC-DC voltage converter (integratedpower cable) 402. In one embodiment, one or more pairs of rail andground conductors 402A of the second end 422B of the power cable 422 arefixedly attached or connected, e.g. by mechanical and/or electricalmeans such as crimping and/or soldering, to a first connector 402B. Thefirst connector 402B is electrically and mechanically connected to asecond connector 402C. In another embodiment, the first connector 402Band the second connector 402C can be mechanically and electricallyconnected and disconnected; as a result, one or more pairs of rail andground conductors 402A of the second end 422B of the power cable 422 arecorrespondingly be electrically coupled and decoupled to and fromcorresponding at least one input 402D, e.g. input terminals, of the atleast one DC-DC voltage converter system 421.

A third connector 402F, which may be part of the at least one DC-DCvoltage converter system 421, is coupled, e.g. fixedly connectedmechanically and electrically, to output terminals 402E of the at leastone DC-DC voltage converter system 421. The third connector 402F can beused to couple the integrated power cable 402, e.g. directly or throughthe at least one second overvoltage protection circuit 125, to theremote radio head 102. In one embodiment, a fourth connector 402G iscoupled, e.g. fixedly connected mechanically and electrically, to thefirst end 422A. In another embodiment, the fourth connector 402G isconfigured to be connected, e.g. to the DC power supply 112 or theredundancy and safety system 113.

FIG. 5 illustrates a block diagram of one embodiment of a co-packagedsystem 500 comprised of a co-packaged first OVP, at least one DC-DCvoltage converter system, and a second OVP. In one embodiment, the firstOVP 523, the second OVP 525 and the at least one DC-DC voltage convertersystem 521 are mounted in and enclosed by the same enclosure 500A. Inanother embodiment, the enclosure 500A is mounted on the tower 106; thistechnique also eliminates the need to mount another component on thetower 106.

The input of the first OVP 523 is configured to be coupled to the secondend 522B of the power cable 522. An output of the first OVP 523 iscoupled to at least one input of the at least one DC-DC voltageconverter system 521. At least one output of the at least one DC-DCvoltage converter system 521 is configured to be coupled to second OVP525. At least one output of second OVP 525 is configured to be coupledto the at least one remote radio heads 102.

Because the voltage conversion by the at least one DC-DC voltageconverter system 521 has a non-ideal conversion efficiency, e.g. ninetyeight percent, some energy is converted to heat, for example by theswitching elements 230E. Therefore there is a need for a mechanism todissipate such heat. FIGS. 6A-6D illustrate diagrams of mechanisms todissipating the heat.

FIG. 6A illustrates a diagram of one embodiment of an enclosure, atleast one DC-DC voltage converter system, and a heatsink 600. Theheatsink 600E is physically attached to the enclosure 600A, andphysically and thermally attached to each DC-DC voltage convertersystem, such as the illustrated DC-DC voltage converter system 621A. Inone embodiment, the heatsink 600 is thermally isolated by the enclosure600A. In the illustrated embodiment, the heatsink 600E is configured tohave up to four DC-DC voltage converter systems attached to the heatsink600E.

In one embodiment, the heatsink 600E has pairs of threaded holes 600C.Each DC-DC voltage converter system has a corresponding pair of throughholes 621B. A pair of threaded bolts 600B is respectively insertedthrough the pair of through holes 621B and screwed into the pair ofthreaded holes 600C. This attachment system not only mechanicallysecures the DC-DC voltage converter system 621A to the heatsink 600E,but as is subsequently described provides good thermal contact.

In one embodiment, a portion of the side of the DC-DC voltage convertersystem 621A that thermally contacts the heatsink 600E is a thermalconductor such as metal. In another embodiment, the first switchingtransistor 230E and the second switching transistor 230F thermallycontact this thermal conductor. In a further embodiment, conductiveheatsink compound, e.g. which may be silicone oil with metal oxidepowder, is applied between the thermal conductor of the DC-DC voltageconverter system 621A and the heatsink 600E.

FIG. 6B illustrates a diagram of another embodiment of a DC-DC convertersystem 621A′. The DC-DC converter system 621A′ includes the previouslydescribed pair of through holes 621B. The DC-DC converter system 621A′also includes a pair of input voltage contacts 621C at one pair ofcorners a first side 621E of the DC-DC converter system 621A′, and apair of output voltage contacts 621E at one pair of corners on a secondside 621F (opposite the first side) of the DC-DC converter system 621A′.In another embodiment, the input voltage contacts 621C are configured toreceive an input voltage of between 380-400V DC. In a furtherembodiment, the output contacts 621D are configured to provide an outputvoltage of +/−3.3 to +/−48V, e.g. −48V.

FIG. 6C illustrates a diagram of an embodiment of the enclosure and theheatsink 604. The enclosure 600A has a backside 600A-land a topside600A-2. The heatsink 600E is attached, e.g. by bolts, screws and/orother attaching mechanisms to the backside 600A-1. The backside 600A-1has an opening 600A about which the heatsink 600E is attached; thisdiminishes undesirable distribution of the thermal energy generated bythe at least one DC-DC voltage converter systems 121 to the enclosure600A, and thus components in the enclosure 600A such as the first OVP122B, the at least one DC-DC voltage converter systems 121 and secondOVP 125. However, the periphery 600E-1 of the heatsink 600E overlaps thebackside 600A-1 (where there is no opening 600G) to facilitateattachment of the heatsink 600E to the enclosure 600A. In anotherembodiment, a thermal insulator gasket 600F is mounted in between theheatsink 600E and the backside 600A-1. The thermal insulator gasket 600Fthermally isolates the heatsink 600 e from the enclosure 600A. In afurther embodiment, the thermal insulator gasket 600F is a siliconerubber, fiberglass, or ceramic cloth or substrate. Alternatively, aconductive heatsink compound can be applied between the heatsink 600Eand the backside 600A-1.

FIG. 6D illustrates a diagram of one embodiment of four DC-DC convertersystems, the first OVP and the second OVP mounted in an enclosure 606.The illustrated view is of the frontside 600A-3 of the enclosure 600E.Each of the four DC-DC converter systems 621A, 621B, 621C, 621D aremounted to the heatsink 600E, e.g. as described above, and coupledbetween the first OVP 623 and the second OVP 625. The heatsink 600E ismounted to the enclosure 600A, e.g. as described above. A high voltageis provided to each of the four DC-DC converter systems 621A, 621B,621C, 621D by first conductors 600G. Each DC-DC converter systemprovides a low voltage output, e.g. isolated from one another oralternatively not, through second conductors 600H.

In one embodiment, at least one interlocking switch (switch(es)) 600I ismounted about the front side 600A-3. In this embodiment, a removablecover plate attaches to the front side 600A-3 to provide service accessto the enclosure 600A. In one embodiment, the at least one interlockingswitch 600I coupled to at least one of the DC-DC converter systems, forexample DC-DC converter system 621A, which include a convertercommunications system 231 configured to communicate with the redundancyand safety system 113; the at least one interlocking switch 600I iscoupled to the communications processing system 231C. When the removablecover plate is mounted on the front side 600A-3, the at least oneinterlocking switch 600I is closed. When the removable cover plate isdismounted from the front side 600, the at least one interlocking switch600I is open. The at least one interlocking switch 600I communicates tothe communications processing system 231C when the removable cover platehas been removed, and the at least one interlocking switch 600I is open.As a result, the communications processing system 231C, e.g. the MCS233, commands the first communications circuit 231B to communicate with,or fails to communicate with, the redundancy and safety system 113 sothat the redundancy and safety system 113 ceases to provide of highvoltage and thus enhances safety and reduces the risk of electrocutionto a person servicing the enclosure 600A.

FIG. 7 illustrates one embodiment of the first over voltage protectioncircuit, at least one DC-DC voltage converter system and the second overvoltage protection in separate enclosures 700. The first over voltageprotection circuit (OVP) 723 is in a first enclosure 700A and coupled tothe power cable 122. The at least one DC-DC voltage converter system 721is in a second enclosure 700B, and is coupled to the first OVP 723 andthe second over voltage protection circuit (OVP) 725. The at least oneOVP 724 is in a third enclosure 700C is coupled to at least one RRU 102.If the at least one DC-DC voltage converter system 721 is in a separateenclosure, then there is more flexibility in heatsink design and room toaccommodate more individual DC-DC voltage converter systems. In anotherembodiment, a heatsink is physically attached to the second enclosure,and physically and thermally attached to each DC-DC voltage convertersystem, such as described above with regards to FIG. 6.

FIGS. 8A-8D illustrate block diagrams of different techniques forcombining at least one DC-DC voltage converter system with one or moreremote radio heads. FIG. 8A illustrates a block diagram of oneembodiment of a combination of at least one DC-DC voltage convertersystem and remote radio head coupled through a converter connector and aRRH connector 804. The at least one DC-DC voltage converter system 821includes a converter connector 821A through which the DC-DC voltageconverter 821 supplies power. The at least one DC-DC voltage convertersystem 821 is coupled to the power cable 122, directly or through thefirst OVP 123. The remote radio head 802 includes a RRH connector 802Athrough which the remote radio head 802 receives power. The remote radiohead 802 is coupled to the at least one antenna 104. In this embodiment,the at least one DC-DC voltage converter system 821 is coupled to theremote radio head 802 by connecting the converter connector 821A to theRRH connector 802A. If the at least one DC-DC voltage converter 821 issecurely attached to the remote radio head 802, e.g. by connectors thatmechanically secure to one another, then this technique also caneliminate the need to mount DC-DC voltage converters, e.g. in anenclosure, on a tower. In another embodiment, the power cable 122 and atleast one DC-DC voltage converter system 121 are implemented asdescribed in and about FIG. 4B hereof. Further, if exposed to theenvironment, a heatsink may not be required to dissipate heat from theat least one DC-DC voltage converter 821.

FIG. 8B illustrates a block diagram of one embodiment of at least oneDC-DC voltage converter 821 that provides power to multiple, e.g. N,separate remote radio heads 802, e.g. remote radio head A 802A throughremote radio head N 802N. The at least one DC-DC voltage converter 821is coupled to the power cable 122, directly or through the first OVP123. Each remote radio head is coupled to the at least one antenna 104.Because the higher voltage is used, many more remote radio heads 802 canbe supplied power for the same power loss over the power cable 122 if alower voltage level had been used.

FIG. 8C illustrates a block diagram of one embodiment of a remote radiohead incorporating at least one DC-DC voltage converter 821Zincorporated in a remote radio head 802A. The at least one DC-DC voltageconverter system 821Z has a first input and a second output. The firstinput is configured to receive a high voltage, e.g. 380V to 400V, forexample from the power cable 122. The at least one DC-DC voltageconverter system 821Z converts the high voltage to a lower voltageprovided at the second output and useable by one or more components ofthe remote radio head 802A. In another embodiment, an input of a frontend system 802Z (e.g. a power amplifier, low noise amplifier, anupconverter, and a downconverter) are coupled to an output of the DC-DCvoltage converter 821Z. Thus, a high voltage, e.g. 380-400V, is providedto the remote radio 802. The at least one DC-DC voltage converter system821Z converts the high voltage to a lower voltage, e.g. 3.3-12V, useableby components of the remote radio head 821Z, such as the front endsystem 802Z. Alternatively, the high voltage is converted to a lowerintermediate voltage, e.g. 48V; the intermediate voltage is subsequentlyconverted two or more times, e.g. by DC-DC voltage converters and/or alow dropout (LDO) regulators, to a voltage level useable by thecomponents. In a further embodiment, an output of the front end system802Z, or remote radio head 802A, is coupled to at least one antenna 104.With this embodiment, no additional hardware need be mounted on thetower 106.

FIG. 8D illustrates a block diagram of one embodiment of a powerdistribution unit (PDU) system 870. The PDU system 870 includes a PDU872 that distributes power, from a power cable 122, to multiple, i.e. N,RRUs 802A-N. In this embodiment, the PDU 872 is co-located with the RRUs802A-N, e.g. on a roof top or a tower. The PDU 872 is coupled to eachRRU by a power jumper. The RRUs 902A-N respectively include high voltageDC-DC converter systems (converter systems) 821A-N so each RRU iscapable of receiving high voltage directly from the PDU 872 via thejumper 874.

FIG. 9 illustrates a block diagram of one embodiment of a redundancy andsafety system (RSS) 913. The redundancy and safety system 913 includes aprocessing system 932, a second communications circuit 934, a secondhigh voltage isolator (HV2) 935, a high voltage switch 936, and a lowvoltage DC power supply 938. In another embodiment, the high voltageswitch 936 is a single pole, triple or quadruple throw switch, e.g.comprising field effect transistors. For example, when the high voltageswitch 936 is a single pole, quadruple throw switch, it has an inputthat is grounded or is left floating so when selected the output of theredundancy and safety system 913 has a zero volt or floating outputvoltage; the zero volt or floating output voltage may be used when theredundancy and safety system 913 is set to a high safety mode. Thesecond high voltage isolator 935 isolates the second communicationscircuit 934 from high voltage at the output of the redundancy and safetysystem 913, while permitting the second communications circuit 934 totransmit and receive data. The second high voltage isolator 935 may be ahigh voltage isolator like those exemplified for the first high voltageisolator 231A. In one embodiment, the second communications circuit 934is the same product as used for the first communications circuit 231B.

The high voltage switch 936 is coupled to the processing system 932, thesecond communications circuit 934 (through the second high voltageisolator 935), the low voltage DC power supply 938, the DC power supply112, the power cable 122, and the battery backup system 115. In oneembodiment, a first voltage sensor 937A, which measures the outputvoltage of the redundancy and safety system 913, is coupled to theprocessing system 932. In another embodiment, the redundancy and safetysystem 913 includes a second voltage sensor 937B, which measures thevoltage provided by the DC power supply 112, is coupled to theprocessing system 932. In another embodiment, the redundancy and safetysystem 913 includes a third over voltage protection circuit (OVP) 933between the output of the redundancy and safety system 913 (or powercable 122) and the first voltage sensor 937 (or high voltage switch936).

In one embodiment, the output voltage of the low voltage DC power supply938 is between a voltage sufficient to power the convertercommunications system 231 and twelve volts, e.g. five volts. In anotherembodiment, the output current of the low voltage DC power supply 938 iscurrent limited to 1 to 100 milliamps, e.g. 10 milliamps.

In one embodiment, the processing system 932 includes a memory 932Acoupled to a processor 932B. The memory 932A and processor 932B may beimplemented, in whole or in part, by a state machine or a fieldprogrammable gate array. In another embodiment, the memory 932A includesa safety system 932A-1 and a backup system 932A-2. In a furtherembodiment, the safety system 932A-1 and the backup system 932A-2 aresoftware executed and/or processed on the processor 932B. The safetysystem 932A-1 controls whether a high voltage from the DC power supply112 is provided, or is not provided, to the power cable, e.g. bycontrolling the position of the high voltage switch 936 and/or usingtechniques described elsewhere herein.

The backup system 932A-2 controls when the battery backup system 115provides power to the power cable in lieu of the DC power supply 112,e.g. by controlling the position of the high voltage switch 936. In oneembodiment, the processing system 932, e.g. the backup system 932A-2, isconfigured to receive the voltage measured by the second voltage sensor937B, and to determine whether the DC Power supply 112 is delivering anadequate voltage level, e.g. above a predetermined threshold level. Ifthe measured voltage is inadequate, e.g. below the predeterminedthreshold level, then the high voltage switch 936 discontinues providingpower from the DC power supply 112 to the remote radio head 102 throughthe power cable 122, and provides power, e.g. from the battery backupsystem 115 to the remote radio head 102 through the power cable 122.

However, the high voltage switch 936 may switch from a high voltageprovided by either the DC power supply 112 or battery backup system 115in the event specific signal(s) are received or no signals are receivedby the second communications circuit 934, e.g. from the firstcommunications circuit 231B. In one embodiment, if the power cable 122is not coupled between the redundancy and safety system 913 and the atleast one DC-DC voltage converter system 121, then no signals will bereceived from the first communications circuit 231B by the secondcommunications circuit 934, and the processing system 932, e.g. thesafety system 932A-1. As a result, the processing system, e.g. thesafety system 932A-1, controls the high voltage switch 936 to couple alow voltage from the DC power supply 938 to the output of the redundancyand safety system 913. Thus, in another embodiment, the DC power supply112 is isolated from the at least one DC-DC voltage converter system121. In yet another embodiment, the DC power supply 112 is isolated fromthe at least one DC-DC voltage converter system 121 for a programmabletime period, i.e. blanking time, before attempting to re-engaging powerto cable 122.

In one embodiment, a removable cover plate is removed from an enclosurehousing high voltage circuitry such as an overvoltage protection circuitor at least one DC-DC voltage converter, and interlocking switch(s) openand cause the first communications circuit 231B to issue a signalindicating such removal. Such a signal is received from the firstcommunications circuit 231B by the second communications circuit 934,and the processing system 932, e.g. the safety system 932A-1. As aresult, the processing system, e.g. the safety system 932A-1, controlsthe high voltage switch 936 to couple a low voltage from the DC powersupply 938 to the output of the redundancy and safety system 913.

In one embodiment, the first voltage sensor 937A serves a feedbacksensor to the processing system so that it can confirm that theredundancy and safety system 913 is outputting the appropriate voltagelevel, low or high. In another embodiment, if the voltage level iswrong, e.g. high when it should be low, then the processing systemissues a warning alarm. In a further embodiment, the redundancy andsafety system 913 commands the DC power supply 112 and/or the batterybackup system 115, through communications link(s), to turn off.

In one embodiment, the redundancy and safety system 913 includes awatchdog timer 939 such as a Maxim Integrated Products, Inc. MAX6369.The watch dog timer 939 is coupled to the processing system 932. Asfurther illustrated below, the watchdog timer 939 may reset theprocessing system 932 in case the processing system 932, e.g. the safetysystem 932A-1, is not properly performing its safety function; forexample, this may be indicated by the processing system 932, e.g. thesafety system 932A-1, not sending a reset signal to the watchdog timer939 before the watch dog time count reaches a threshold level.Transmission of the reset signal by the processing system 932, e.g. thesafety system 932A-1, indicates that the processing system 932 isfunctioning properly.

FIG. 10 illustrates a flow diagram of one embodiment of operation of aredundancy and safety system 1060. To the extent that the embodiment ofmethod 1060 shown in FIG. 10 is described herein as being implemented inthe systems shown in FIGS. 1 through 9, it is to be understood thatother embodiments can be implemented in other ways. The blocks of theflow diagrams have been arranged in a generally sequential manner forease of explanation; however, it is to be understood that thisarrangement is merely exemplary, and it should be recognized that theprocessing associated with the methods (and the blocks shown in theFigures) can occur in a different order (for example, where at leastsome of the processing associated with the blocks is performed inparallel and/or in an event-driven manner). For purposes of clarity, theredundancy and safety system exemplified herein may or may not include aredundancy function.

In block 1062, boot a redundancy and safety system, e.g. a redundancyand safety system 113. In one embodiment, during this block, the outputvoltage of the safety system is disabled and an open circuit. In anotherembodiment, during this block, the output voltage is the output voltageof the low voltage power supply 938. In a further embodiment, thecorresponding output current is current limited. In yet anotherembodiment, the first voltage sensor 937A measures the voltage at theoutput of the redundancy and safety system, e.g. when a low voltage isapplied to the output of the redundancy and safety system. If themeasured voltage is substantially less than the low voltage, e.g.substantially zero volts, then a short circuit condition is detected bythe redundancy and safety system, e.g. the safety system 932A-1.

In block 1064, determine if the redundancy and safety system bootedproperly. In one embodiment, this entails the redundancy and safetysystem, e.g. the safety system 932A-1, determining if there is a shortcircuit at the output of the safety system.

If the redundancy and safety system was determined to not have bootedproperly, then return to block 1062. In another embodiment, issue awarning that the redundancy and safety system failed to boot properly.If the redundancy and safety system was determined to have bootedproperly, then proceed to block 1066 or block 1068.

Optionally, in block 1066, if it is not already doing so supply lowvoltage, e.g. from the low voltage DC power supply 938, to the output ofthe redundancy and safety system. Optionally, in block 1067, initiate awatch dog timer (WDT) 939.

In block 1068, initiate communications, e.g. with at least one DC-DCvoltage converter system 121 configured to power at least one remoteradio head 102. In another embodiment, initiating communications meanssending query messages, e.g. from the second communications circuit 934over the power cable 122 to the first communications circuit 231B. In afurther embodiment, send such query messages that are requests foracknowledgement. In yet another embodiment, send query messages at arate of at least two per second, e.g. five per second.

In block 1070, determine if communications have been established, e.g.with at least one DC-DC voltage converter system 121. In anotherembodiment, determine if communications have been established bydetermining if at least one acknowledgement (ACK) have been received bythe second communications circuit 934 from the first communicationscircuit 231B. In a further embodiment, each acknowledgement is sent witha cyclic redundancy checksum (CRC), e.g. included in a check value. Inyet another embodiment, the processing system 932A, e.g. the safetysystem 932A-1, evaluates the CRC to ensure that an ACK was trulyreceived, and is not an error.

In one embodiment, only when the redundancy and safety system has justbooted up, send a message, e.g.—from the safety system 932A-1 throughthe second communications circuit 934, over the power cable 122, throughthe first communications circuit 231B, and to the measurement andcontrol system 233—to switch the converter communications system 231from a low voltage mode to a high voltage mode. In another embodiment,upon receipt of such a message, switch the converter communicationssystem 231 to a high voltage mode from a low voltage mode. In a furtherembodiment, send a message, e.g. from the converter communicationssystem 231 acknowledging that it is ready to receive a high voltage fromthe redundancy and safety system.

If communications have not been established, e.g. because the powercable 122 has not been connected, e.g., to the at least one DC-DCvoltage converter system 121, then return to block 1068. Optionally, ifcommunications have not been established and before returning to block106, then in block 1071 supply a low voltage, e.g. from the low voltageDC power supply 938, to the output of the redundancy and safety system913 and the power cable 122. If communications have been established,then proceed to block 1072.

In block 1072, supply a high voltage, e.g. from the DC power supply 112to the output of the redundancy and safety system 913 and the powercable 122. Then, return to block 1070.

When block 1067 is used, then from block 1067 also proceed in parallelto block 1073. In block 1073, determine if the watch dog timer totaltime has elapsed. For, example, the watch dog timer total time is oneminute; however, this amount can vary and be selected by a user orsystem designer.

If the watch dog timer total time has elapsed, then return to block 1062and re-boot the redundancy and safety system. If the watch dog timertotal time has not elapsed, then in block 1074 determine if the watchdog timer 939 received a reset signal, e.g. from the processing system932, processor 932B, or from the safety system 932A-1. The reset signalmay originate as an alarm or another fault indicator. The reset signalresets a timer or counter of the watch dog timer 939 to its starting, orinitial, time. As long as the processing system 932, processor 932Band/or the safety system 932A-1 operates normally, the processing system932, processor 932B or from the safety system 932A-1 will periodicallyissue the reset signal.

If the reset signal is received by the watchdog timer 939, then in block1076 reset the watch dog timer time to the starting time and return toblock 1074. If the reset signal is not received by the watchdog timer939, then in block 1076 change the watch dog timer time, e.g. byincrementing or decrementing the timer by a fixed amount and return toblock 1073.

EXEMPLARY EMBODIMENTS

Example 1 includes an integrated power cable, comprising: a power cablehaving a first end and a second end; wherein the first end is configuredto be electrically coupled to a DC power supply; at least one DC-DCvoltage converter having at least one input and at least one output;wherein the second end is fixedly electrically and mechanicallyconnected to the input; a first connector fixedly connected mechanicallyand electrically to the output; and wherein the first connector isconfigured to be coupled to at least one remote radio head.

Example 2 includes the integrated power cable of Example 1, wherein atleast a portion of the at least one DC-DC voltage converter system andthe second end are covered by an insulator.

Example 3 includes the integrated power cable of any of Examples 1-2,wherein a second connector is fixedly connected mechanically andelectrically to the first end.

Example 4 includes the integrated power cable of any of Examples 1-3,wherein the at least one DC-DC voltage converter system comprises asynchronous step-down converter.

Example 5 includes the integrated power cable of any of Examples 1-4,wherein the at least one DC-DC voltage converter system comprises aconverter communications system

Example 6 includes a power cable, comprising: a power cable having afirst end and a second end; wherein the first end is configured to beelectrically coupled to a DC power supply; at least one DC-DC voltageconverter having at least one input and at least one output; a firstconnector fixedly electrically and mechanically connected to the secondend; a second connector fixedly electrically and mechanically connectedto the at least one input; wherein the first connector is coupled to thesecond connector; and a third connector fixedly electrically andmechanically connected to the at least one output; and wherein the thirdconnector is configured to be coupled to at least one remote radio head.

Example 7 includes the power cable of Example 6, wherein a fourthconnector is fixedly connected mechanically and electrically to thefirst end.

Example 8 includes the power cable of any of Examples 6-7, wherein theat least one DC-DC voltage converter system comprises a synchronousstep-down converter.

Example 9 includes the power cable of any of Examples 6-8, wherein theat least one DC-DC voltage converter system comprises a convertercommunications system

Example 10 includes an apparatus, comprising: a first overvoltageprotection circuit having a first input and a first output, andconfigured to be mounted on a tower proximate to at least one remoteradio head; at least one DC-DC voltage converter system having at leastone input coupled to the first output, and at least one output; a secondovervoltage protection circuit having a second input coupled to the atleast one output, and a second output coupled to at least one remoteradio head; a first enclosure enclosing the at least one DC-DC voltageconverter system and configured to be mounted on the tower proximate tothe at least one remote radio head; wherein the first input isconfigured to be coupled to a power cable; and wherein the at least oneoutput is configured to be coupled to the at least one remote radiohead.

Example 11 includes the apparatus of Example 10, further comprising aheatsink mechanically attached to and thermally coupled to each of theat least one DC-DC voltage converter system, and mechanically attachedto and thermally insulated from the enclosure.

Example 12 includes the apparatus of Example 11, wherein the heatsink isthermally coupled to each of the at least one DC-DC voltage converterwith conductive heatsink compound.

Example 13 includes the apparatus of any of Examples 11-12, wherein theheatsink is thermally isolated from the enclosure with a thermalinsulating gasket.

Example 14 includes the apparatus of any of Examples 10-13, wherein theat least one DC-DC voltage converter system comprises a synchronousstep-down converter.

Example 15 includes the apparatus of any of Examples 10-14, wherein theat least one DC-DC voltage converter system comprises a convertercommunications system.

Example 16 includes the apparatus of any of Examples 10-15, wherein thefirst enclosure or a second enclosure encloses the second overvoltageprotection circuit.

Example 17 includes an apparatus, comprising: a remote radio head,comprising: at least one DC-DC voltage converter system having a firstinput configured to receive a voltage between 380V and 400V and anoutput configured to provide between Example 3.3V and 48V; and a frontend system having a second input coupled to the output of the at leastone DC-DC voltage converter system; and wherein the first input isconfigured to be coupled to a power cable.

Example 18 includes the apparatus of Example 17, wherein the at leastone DC-DC voltage converter system comprises a synchronous step-downconverter.

Example 19 includes the apparatus of any of Examples 17-18, wherein theat least one DC-DC voltage converter system comprises a convertercommunications system.

Example 20 includes the apparatus of any of Examples 17-19, wherein thefront end system comprises at least one of a low noise amplifier, apower amplifier, an upconverter, and a downconverter.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement, which is calculated to achieve the same purpose,may be substituted for the specific embodiments shown. Therefore, it ismanifestly intended that this invention be limited only by the claimsand the equivalents thereof.

The invention claimed is:
 1. An integrated power cable, comprising: a power cable having a first end and a second end, where the second end is configured to be on a mounting structure; wherein the first end is configured to be electrically coupled to a DC power supply; at least one DC-DC voltage converter having at least one input and at least one output; wherein the second end is fixedly electrically and mechanically connected to the at least one input; a first connector fixedly connected mechanically and electrically to the at least one output; wherein the first connector is configured to be coupled to at least one radio; and wherein the at least one DC-DC voltage converter is configured to provide lower voltage to the at least one radio having a voltage level lower than the voltage provided by the DC power supply to the at least one DC-DC voltage converter.
 2. The integrated power cable of claim 1, wherein at least a portion of the at least one DC-DC voltage converter system and the second end are covered by an insulator.
 3. The integrated power cable of claim 1, wherein a second connector is fixedly connected mechanically and electrically to the first end.
 4. The integrated power cable of claim 1, wherein the at least one DC-DC voltage converter system comprises a synchronous step-down converter.
 5. The integrated power cable of claim 1, wherein the at least one DC-DC voltage converter system comprises a converter communications system.
 6. An apparatus, comprising: a first overvoltage protection circuit having a first input and a first output, and configured to be mounted on a mounting structure proximate to at least one radio; at least one DC-DC voltage converter system having at least one input coupled to the first output, and at least one output; a second overvoltage protection circuit having a second input coupled to the at least one output, and a second output coupled to at least one radio, and configured to be mounted on a mounting structure proximate to at least one radio; a first enclosure enclosing the at least one DC-DC voltage converter system and configured to be mounted on the mounting structure proximate to the at least one radio; wherein the first input is configured to be coupled to a power cable; and wherein the at least one output is configured to be coupled to the at least one radio.
 7. The apparatus of claim 6, further comprising a heatsink mechanically attached to and thermally coupled to each of the at least one DC-DC voltage converter system, and mechanically attached to and thermally insulated from the enclosure.
 8. The apparatus of claim 7, wherein the heatsink is thermally coupled to each of the at least one DC-DC voltage converter with conductive heatsink compound.
 9. The apparatus of claim 7, wherein the heatsink is thermally isolated from the enclosure with a thermal insulating gasket.
 10. The apparatus of claim 6, wherein the at least one DC-DC voltage converter system comprises a synchronous step-down converter.
 11. The apparatus of claim 6, wherein the at least one DC-DC voltage converter system comprises a converter communications system.
 12. The apparatus of claim 6, wherein the first enclosure or a second enclosure encloses the second overvoltage protection circuit. 